【摘要】 对碳纳米管纱束在不同加载条件下的拉伸疲劳行为进行了研究，采用SEM、TEM、拉曼光谱、DMA等系统地表征了纱束在疲劳前后的微观结构及性能演化规律。发现了其新奇的疲劳特性，得到了相关疲劳失效机制。结果表明：碳纳米管纱束耐疲劳性符合传统幂律关系，疲劳强度为413 MPa,疲劳比为0.51。不同于单根碳纳米管，纱束疲劳失效存在渐进损伤累积过程，且其耐疲劳性会受到加载频率影响，5,7,27 Hz加载频率下耐疲劳性相比于附近频率提升十倍甚至百倍，呈现非单调极值响应现象。纱束的疲劳性能与其阻尼性能存在强相关性，在5,7,27 Hz加载频率下耐疲劳性的大幅提升归因于类高分子玻璃化转变或次级转变提升了纱束的阻尼性能。更多还原

【Abstract】 The fatigue behaviors of carbon nanotube(CNT) yarn bundles under different cyclic loading stress levels, loading frequencies and temperatures were studied.The microstructure and performance evolution of the bundles were systematically characterized by SEM,TEM,Raman spectroscopy and DMA.The novel fatigue behaviors for these yarns were discovered.Based on these analysis, the fatigue failure mechanism and key influencing factors were obtained.The results show that the fatigue resistance of CNT yarn bundles conforms to the traditional power law relationship.The fatigue strength is 413 MPa and the fatigue ratio is 0.51.Unlike single carbon nanotubes, the fatigue failure of CNT yarn bundles has a progressive damage accumulation process.The loading frequency has significant effects on the fatigue resistance of the yarn bundles.The fatigue resistance at the loading frequency of 5,7,27 Hz is ten times or even a hundred times higher than that at the nearby frequency and a novel phenomenon of non-monotonic extremal response is presented.There is a strong correlation between the fatigue performance of CNT yarn bundles and their damping performance.The substantial improvement of fatigue resistance at the loading frequency of 5,7,27 Hz is attributed to the improvement of the damping performance of the yarn bundles due to the occurrence of polymer-like glass transition or secondary transition.更多还原